Automatic telephone-switch



H. G. WEBSTER. AUTOMATIC TELEPHONE SWITCH.

I APPLICATION man APR. 19, 1916. 1,390,409. PatentedSept. 13,1921.

2 SHEEIS-SHEE! I.

H- G. WEBSTER.

AUTOMATIC TELEPHONE SWITCH.

APPLICATION FILED APR- 9; 1916- 1,390,409. PatentedSept. 13, 1921.

2 SHEETS-SHEH 2.

Emile/hi0) UNITED vsrA s PATENT or ce.

HARRY e. WEBSTER, or CHICAGO, ILn I'NoIsQ 1" AUTOMATIC TELEPHONE-SWITCH,7

Specification of Letters Patent.

Patented se t. s, 1921;

i vApplication filed April 19, 1916. Serial No. 92,080.

To all to hom it may concern Be it known thatI, HARRY G. .Wnns'rER, acitizen of. the United States, residing at Chicago, in the county ofCookand State' of Illinois, have invented a certain new and usefulImprovement in: Automatic Telephone-Switches, of which the following isa full, clear, concise, and exact description, referencebeing had to theaccompanying drawings, forming a part of this specificalustrated theswitch, contain points of novelty, some 'of-whichare hereinafterclaimed,

iing an improvement that render the particular system-especially usefulin connection with the switch, I do not intend to limit the'switch touse 'in connection with those particular circuits whet-her used for theabove, or other analo gous purposes.

The switch which I have illustrated is a rotary uni-planar steppingswitch, formupon ofis'witch shown and described in the patent to, Sidney.Hand Browne, No. 1,073,589,

granted September23,1913. The novel features pointed out in the appendedclaims are, however, applicable to other types of switches.

It has been customary heretofore to provide a stepping ratchet and aholding pawl which pawl. is' controlled by a release magnet. e Thepresent invention dispenses with the release magnet and transfers thefunction of effecting restoration or release to the step-controllingmagnet; This permits of a less expensive construction. It also securesan even wear upon the contacts and terminals besides securing otheradvantages. a' predetermined position to prepare it 'for anotherselective operation.

the specific type I to normal,

The switch is automatically set to.

The system, in connectionwith whichpI have illustrated the invention,provides a. novel method of controlling. the test circuit which governsthe connection of a switch. with the proper terminal.-: The. function ofthis novel method of controlis to secure greater reliability andcertainty-of-iaction than has been consideredpossiblein systems of thisclass as heretoforeconstructed. In

the accompanying drawings which form a. part of the presentspecificatiom-I'have' illustrated one embodiment of my invention,

in a'uni-planar rotary steppingswitch em ployed in a trunk-selecting,call-distributing telephone system. 1. Figure 1 is a plan view of aswitch,

Fig. 2 is a front elevation ofthe same;

.Fi 3 isa horizontal sectiontaken on the 3 line 3,3,ofFig.2-;and Fig. 1is axcircuit diagram of a system employing the switch shownv in Figs.1,2 and'3." The switch shown in Figs. 1, 2 and- 3 com prises the frameplates 1 and 2,:which are provided with suitable bearings 3and1 1,re-"spectively, for mounting acentralzspindle or shaft 5 which bears the'wipersE6, 7, 8 and 9.

maintain; separate independent circuits; The frame plates 1 and 2 haveclamped betweenthem. by meansof the bolt 10; a-pl'u rality ofsemi-circular rows of contacts corresponding in number to the wipers 6,7,8 and 9. These contacts 11 are arrangedin vertical. rows which rowsare grouped inthe arc of a circle, as is'wellunderstood in'the art. Thecontacts 11aresuitably-insulated from each other and from the 'frame ofthe' switch. Theupperend of'the spindle or shaft 5 bears a ratchet wheel15' having a suitable number'of teeth to provide a stepping toothforeach position of the-group of wipers. -The ratchet wheel 15isadv'ancedby means of thestepping magnet 16"which mally out of contact with theteeth of-the ratchet wheel 15 by means of thespring:18 and-the pin 19.A- holding paw1120,-controlled by a suitable spring 21 =is provided tohold the ratchet-wheel 15: in such position that the wiper groupwillremain in'contact with the desiredterminalsl The pawl 20 is providedwith an extending tail aazwhieh normally lies in front ofthe end" of theThese wipers are insulated" from the" shaft 5"and from eachother-inorderto has a suitable stepping pawl. 17 heldnor-i 26, shown indotted line in Fig. 1, which springs tend to move the shaft and theattached-wiper group back to zero position.

A pair'of off-normal springs 27 and 28 are mounted on a block ofinsulation 29 on the top plate lin such position that the off-normal pin30 may engage the longer sprin'g27 to hold the springs 27 and 28 in opencircuit position when the wiper group is at zero.

The longer spring 23 is provided with a projection 32which is adapted tobe engaged by an arm of insulating material 33 when theratchet wheel .15is returned to the zero position. The ratchet wheel 15 is provided.

with a suitable number of teeth corresponding to the steps of the switchso that when the wiper group is incontact with the last terminal groupand an additional step of the stepecontrolling magnet 16 is caused thelarge releasing projection or tooth 34throws the pawl 20 outward farenough for the tail 22 to drop back ofthe projection 24 on the springs23 and thus be held out of operative position. Thespring 26then returnsthe shaft 5 andthe wiper group to zero. Just beforethe shaft returnscompletely to the zero position thearm 33 engages the projection32.0n'thelor1ger spring 23, forcing-the spring outward and therebyreleasing the tail 22 ofthe pawl 20 and causing the'pawl to be cast intothe teeth of-the ratchet 15.

Fig. 4 illustrates a call-distributing telephone system employing ;theswitch above described, Each subscribers line is provided at centralwith a trunk selecting swi-tchof the above type. scriber at the stationA, which is assumed to be the calling subscriber, closesthc circuit ofthe line wires 40 and 41, by bridging'the telephone instrumentthereacross,- a circuit is closed for the line relay42 over thefollowing path V V vFrom the common battery B through the line. relay42, back armature contact 43 of the cut-off relay 44, over the line wire40 through the instrument bridge at the substation A, line wire 41through back armature contact 45 to ground at'46. The line relay 42pulls up the two armatures 46 and 47 a'gainst the front contacts, thefirst con tactclosing a. ground for testing purposes when the switch hasstepped fronrthe normal position, as will be described later.

The other armature 47 closes the circuit The tail 22 of the- When thesub for the stepping magnet 16. The time of the stepping magnet may betraced as follows p From battery B through the interrupter 48 throughthe winding of the magnet 16,

armature 47 and front contacts thereof, wire 49' and to ground throughthe backcontact of the cut-off relay armature50.-' -The' 'step-' pingmagnet is alternately energized and deenergized thereby stepping thewipers 6, 7,

8 and 9 from the zero position forward ina armature contact 59, throughthe back armature contact 60 of the slow release relay 61, over theprivate 'wire'62 of the particular trunk T, which has been selected,through thewiper 8, third wire 63, through the wind ings 64 and 65 ofthe cut-off relay 44 in series, to ground by way of the armature contact46, or by way of the wire66 and wiper 9 to ground. It will be observedthat the wiper 9 maybe replaced by suitable off-normalcontacts,-as itsfunction is merely to supply a suitable ground for ener izing thecut-off relay 44 when the line of a subscriber A is connected to bymeans of suitable plug and j ackconnection, under the condition thatthis lineis the called line. 7

When the above-traced circuit of the relays 44 and 55 is closed, both ofthe relays are energized. The relay 44 attracts its arna ls of thestepping magnet 16, thereby stopping further. movement of the. switchand at the same time closing the armature 50 against the front contactshunting out the winding 64 of the relay 44, leaving only the winding 65in circuit. The windingf65 of the relay 44 has ample power to hold thearmature in attracted tures 43 and 45 are attracted, the line; wires 46and 41 are connected through the exten sions 67 and 68v with the strands69 and 70 of the linkcircuit P.

=At the same time that therelay 44 is energized the relay 55 attractsits armatures 59 and 71. "The armature 71 closes the circuit of thesignal lamp 72 which serves at this time as a call lamp, indicating tothe operator that the trunk T has been selected by the automatic switchof the calling party. The other armature 59 of the relay 55 is attractedto open the shunt about the wind- 4 ing 57. It. will-be seenfthat thetwo relays.

44 and 55,.which are included in the test circuit, cooperate toincrease-the margin of position. As the armaconnection of the wiperthrough the testing.

operation of the test-circuit. The cut-off relay 44 is employed as atesting relay, operating. upon a margin of potential. Ifthe contact 53had been selected by and connected to a wiper of one selecting switch,the

potential of the contact should have been so much lowered or modified bythe ground relay, which'selected the particular wiper,

that a second switch in testing the contacts would not find sufficientpotentialto energize its cut-off relays and thus be stopped upon thesame contact By causing the-two relays 44 and to coiipera'te to' cut outa part of the winding of one and to cut in a part of the winding of theother, I am able to shift the gradient of potential, with 'respectto thecontact 53, to such an extent that the margin between a busy contactandan idle contact 1s very large. At the same time the current'fiowiintherelay 44.0f-the busy line is not larger or substantially larger thanwhen the relay is first-energized, but is ample, to hold the armaturesin attracted position. For instance, assume that the windings 64 and 56are of 200 ohms each and thatv the windings and 57 are of 300' ohmseach. The total resistance in the circuit at the time that therelaysare-Lenergized is 700 ohms. The contact 53'is at 100% batterypotential before the wiper 8 comes upjon it. As soon as the wiper restsupon the contact 53 and before the armatures are shifted, the potentialofthecontact 53 is about 71% of full battery voltage. The-relays are sodesigned and the voltage so adapted that this voltage is assumed to benecessaryfor the operation of the windings .64 and-65 in series. Whenthe armatures 50 and 59 are shifted the contact53 is reduced toapotentialzof about 29% of full battery voltage which would beinsuiiicient to energize the windings 64 and 65 of another relay.

I do not wish to be limited. to these par ticular values or proportionsof resistance and potential.

- cures greatercertainty of operation than- It can be seen that thearrangement seany known previous marginal testing circuit.

The relay 44 is provided with suflicient am-" pereturns when it firstoperates to insure quick operation and promptstopping'of theswitchuponthe'contact'selected. After-the armatures-are attracted'asmaller number.

of ampere turns are required to hold the armatures up. If the relay 55s'houldbe a, bit slow in operating, the raising of the, armature contact50 will accelerate and insure the operation. of relay 55 by lowering theresistance of the circuit 'andthus increasingv the flow of current untilthearmature 5.9 is attracted to break the shunt about the winding.57..As the wipers 6,7,8 and 9 are stepped away fromzero or normal position,the ofinormal contacts 27 and 28 are closed.

upon the contacts 51, 52, 53 and 54, the supervisory relays 73 and 74are energized'by being included in series with the line cir-. cuit ofthe calling subscriber A.

The operator perceivingthe signal given by the lamp 7 2 connectshertelephone set 75 to the corresponding link circuit and inquires ot thecalling party the number of the desiredsubscribers line with whichconnection is to be made. Assume that the line of the party B isdesired. The operator ine serts the plug 76. into one of the jacks 77 ofthedesired line and projects ringing cur rentwove'r the called line.When the plug 76 is inserted in the jaclnthe sleeve of the plug makescontact with the thiinble of the jack closing circuit for the cut-offrelay 44. The energizins circuit of the cut-off relay may be tracedII'OI'II battery 13 through the sleeve supervising relay 78 over thesleeve side of the link circuit over the third wire 80 through the,windings'64 and 65 in series to ground 1 at the wiper 9". The cut-ofirelay '44 attracts its armatures shunting out the winding 64 and leavingthe winding 65 in series with the ground armature 50,. It is apparentthat the thimble of the jack 77 would test busy if the line of asubscriber B were'employed as a calling or as a called line. The sleevesupervisory relay'78 attracts its armature 81 thereby closing a circuitfor the slow release relay 61 whichv substitutes itself for, the "relay55. W hen the armature contact 81 is closed the relay 61 is energizedover the following circuit: TY

Batter-y B, relay .61,'ar1nature contact 81, private-wire62', third wire63, through the winding 65 of the relay 44 to ground by way ofthearmature contact 50. Energization 60 thereby deenergizing the relay 55.This causes the. armature 71 to drop back and efface'th'e callingsignal72. r The armature 82 of the relay 61 is attracted closing a circuitforthe supervisory lamp signal 83in series with theback armature contact.8401- the tip supervisory relay 85.

When the called partyanswers, the tip supervisory relay 385:1S energizedand the lamp 83 is extinguished. When the con versation is finished theparties'place their receivers-.upon the switch hooks thereby breakingthe energizing circuito f' the respective tiprf supervisory .relays. Asthe sleeve supervisory relay 78 remains energized, due to the, circuitthrough. the third wire 80, the lamp signal 83 will again be energizedby droppingaback of the armature contact 84 0f thetip supervisory relay85.

Tiis lights the supervisory lamp 83 indicating disconnection to theoperator. When the plug 76 is withdrawn, the sleeve supervisory relay isdeenergized breaking the circuit or the slow release relay 61. The relay61 is made a slowrelease relay as by means of a copper jacket or theequivalent to cause it to retainits armature in attracted position for ashortperiod of time after the energizing circuit is broken. This slowrelease is desirable topermit the relay 4A to be deiinergized to releaseits armature. That is to say since the armature contacts 81 and 60 areboth open, the relay 4% becomes deenergized releasing its armatures 45,43 and The armature drops back against the back Contact closing thestepping circuit for the magnet 16 through the oiif-normal contacts 27and 28 which are closed due to tl e off-normal position of the switch,through the contacts 25 and 23 which are held closed by the tail 22 ofthe pawl 20 through the back armature contact 47, Wind ing of thestepping magnet 16, through the interrupter a8 and to battery B. Theswitch is then stepped forward to release. The above stepping circuitremains closed until the pawl 20 is tripped out of the ratchet by thetooth 84C. The tail of the pawl drops off of the shoulder 24 and is heldout of contact with the ratchet. The spring 26 immediately moves theshaft back to the zero position. As the switch approaches zero, the arm33 engages the pin or stud 32 and forces the long spring 23 outward torelease the tail ot the pawl 20 and to close the spring 23 against theback contact 25. At the same time the pin 30 on the ratchet wheel 15moves the longer spring 27 away from the back contact 28 breaking thecircuit of the stepping magnet at this point.

The switch is then in condition to be actuatcd to make another selectionwhen the same is desired. a

It will also be apparent that if all the trunks are busy at the time aswitch is opcrating to select, the wipers will continue their advanceover all the contacts 51, 52 and 53 until they reach the end of the rowwhereupon the release mechanism comes into play and the wipers restoreand immediately start their advance again, until an idle trunk T isselected. It will also be seen that a switch will thus reciprocate insuch release and advance operations until an idle trunk is reached.

The system that I have above described is characterized by simplicityand certainty of operation. The cut-off relay is employed as atesting'relay anddue to the arrangement of cooperation between therelays 44c and 55 the margin of potential is so greatly increased aS toinsure certainty of operation under all normal conditions.

I wish it to be understood that instead of employing a horse-shoe magnetfor the stepvping magnet 16, as I have shown in Figs;

1 and 2, I intend also'to employ a single winding for the magnet 16 inwhich case the bracket 86 and the armature bar 87 are made of magneticmaterial to form substantially a complete magnetic circuit. The advantage of'this form of stepplng magnet-1s that the overall thickness ofthe switch may 7 be materially reduced when space is a valuableconsideration. In addition it will be noted that only a single air gapwill be neces sary in the latter torm as compared with two air gaps whena horse-shoe form of magnet is employed.

I find that the windings'tlet and 57 may be replaced with deadresistance which may be disposed upon the cores of the relays or pawlfor engaging said ratchet, a holding pawl for engaging said ratchet,said ratchet. having a projecting tooth or arm for moving said retainingpawl away from said' ratchet, a spring for engaging'said pawl to holdthe same away'from the ratchet, and means operated by return of theshaftto normal to release said spring.

2. In combination, aplurality of stationary contacts, a plurality ofmovable wipers adapted to make contact with said stationary pawl fromsaid contacts, a shaft for controlling said wipers,

a ratchet for the shaft, a stepping magnet for operating said ratchet, apawl normally engaging said ratchet, said ratchet having meansforthrowing said pawl outward, means for holding said pawl outward, saidmeans controlling the circuit of the stepping magnet.

3. In combination, a bank of contacts, a

wiper forsaid contacts. movable in a. single plane only, a controllingratchet member fiX- edly'secured to said wiper, driving means for movingsaid member from zero through a predetermined range of movement, a pawlto hold the ratchet member in intermediate means actuated by the drivingmeans for preparing the driving means for subse quently restoring thewiper, and means conpositions corresponding to said contacts, 1

ditioned by movement of said ratchet mem-' her to the limit of its'rangeto restore said I ratchet and wiper to .zero.

4. In combination a bank of contacts, a

wiper adapted to be moved over said contacts, a controlling ratchetmember for said wiper, said member being movable from zero through apredetermined range oi movement, a stepping magnet, a' circuit for saidmagnet, a pair of contacts in said circuit, Said contacts being openedby movement of said ratchet to the limit of movement-,means forrestoring said ratchet memher to zero and means for holding the contactsopenuntil said ratchet returns to zero.

5. In combination a bank of contacts, a

wiper adapted to be moved over said con- 1 6. In combination a bank 01":contacts, a

turnstozero. V 8. In a switch of the class described, a ratchet member,a stepping magnet a controlling spring for said magnet, said springwiper adapted to be moved over said contacts, a controllingratchetmember for said wiper, said member being movable from zerothrough a predetermlned'. range of movement, a stepping magnet for saidratchet, a circuit for said magnet,'a pair of contacts in said circuit,a pawl to hold the ratchet member in any intermediate posi-I tion, meansconditioned by movement of said ratchet member to-limit of its range ofmovement to disengage said pawl from said ratchet and to open saidcontacts, said pawl and said contacts being interlocked: until saidratchet member returns. to zero, and means controlled by said ratchetmember to throw the pawl-into engagement with the ratchet and to closesaid contacts.

7. In combination, a bank of contacts, arranged in the arc of asemi-circle, aswiper. adapted to be moved over said'contacts, a ratchetmember, a'shatt connecting said ratchet member and said wiper, saidratchet member being movable from zero through a predetermined range ofmovement, a restoring spring connected tojsaid shaft, a pawl adapted tohold the ratchet member in any intermediate position, said ratchetmember having means for-disengaging said pawl when the ratchet is at thelimitof its movement, a stepping magnet, a circuit for said magnet, acontrolling. spring in said circuit, saidspring havingv meansinterlocking with said pawl for" holding the pawl away from the ratchetuntil said ratchetrehaving a shoulder, said pawl having a tail,

saidshoulderand said tail-being adapted to interlock, saidratchet-memberbeing adapted to be moved from zero to a predetermined positionpand aspring for returning said ratchet to zero" position,'-islaid ratchethaving means adapted when; the ratchet is moved to the limit ofits-range of movement to placeithepawl under the control of said springandfhaving further means adapted when 'said- 'ratchet is re= turnedtozero to lace said spring "under the control of said pawl-1 a 3 9. Inaswitch a ratchetmember', a step j ping magnet for said ratchetmember,-'a pawl, a spring for controlling the circuit of said steppingmagnet," said ratchet have ing means-adapted to throw said pawl out ofaction at one limit of the rangesofimove ment and having turther-imeans'for causing said pawl .to engagesaid' ratchet-t at Ethe other end of therange of movement, said spring being. controlled by said-pawl;-

lO.--In combination an automatic switch,

a line controlling the. switchysaid switch having a privatewiperfand::a-plurality of private contacts, stepping means for-cause ingsaid switch to move "over said contacts,

a testing circuit adapted to. be. closed by said. wiper and one of saidcontacts, 'a cutoff relay controlling-said. stepping I means,

and controlling the normal connections lot the line, said relay-beingconnected-in series a relation with. said wiper, a controlling re-j' layconnected to one of saidpriv ate. con; tacts, one of said relayscomprising an armature adapted-awhen attracted. to :cut' out a portionof its winding and establish a local lockingcircuit to eliminate apredetermined amount ofresistance 1 from --said testing circuit, andthef other otisaid relays havingan armature adapted-when energized toinclude 'a predetermined .amountvof -re-u sistance in saidtestingcircuit. i I 3 11. In combination an automatic selecting switch,a line controlling the :switch, said switchhaving a private wiper and aplu rality of private contacts adapted to be en gaged by saidwiper, atesting-circuit. adapt ed to becloscd by saidwiper andone of saidcontacts, means for causing said switch to move over said contacts, saidmeans comprising a step-controllingmagnet, 'ascut-off' relay controllingsaid step-controlling magnet and controlling the. normal connections ofsaid ,line, said relay;being connectedto saidwiper, and a controlling"relay connectedtoone of said private contacts said relaysf cooperatingto shittthe "gradient of poten u tial of said connected contacts to increa sethe margin of operationvby establ shingva lockingpircuit through.aportion. of the windingofone relay andcutting in an addi-- tionalwinding on the other..- i

, ing a restoring advance of the switch, means individual to the linkcuit'terminals banked in for throwing said pawl out of action at one endof the range of movement, a spring for restoring said ratchet member andmeans for throwing said pawl into action at the otherlimit of the rangeof movement.

13. In a switch, a single row of stationary contacts, a wiper movablealong in engagement with said contacts, a ratchet member having motionin a-single plane, a pawlfor said ratchet, a single stepping magnet, anenergizing circuit for the stepping magnet having acontact closed oninitial actuation of said'magnet subsequently effecting a restoringadvance of the switch,and means controlled by said stepping magnet fordisengaging said pawl from said ratchet while the ratchet returns tozero,

e 14. In combination, a circular contactbank, a rotarywiper, a ratchetfor driving the wiper, a stepping magnet having a paw for driving theratchet, a holding pawl for the ratchet, a projecting member connectedto the ratchet for disengaging the holding pawl, a catch for blockingthe holding pawl away from the ratchet and means connected to theratchet for disengaging the blocking means when the wiper is restored tozero.

15. In combination, a line terminating in an automatic switch,aplurality of link circuit terminals banked in said switch, a linecut-off relay individual to the line, a relay I circuit selected, saidswitch having a wiper adapted to put the line cut-off relay in serieswith the link circuit relay, means including a driving circuit foradvancing the wiper, said circuit including normally closed contacts oftheline cut-ofi' relay, and a calling signal controlled by the linkcircuit relay. 7

16. In combination; a line terminating in an automatic switch, aplurality of link cirsaid switch, a line cut-oif relay'indiv-idual-tothe line, a relay individual to the link circuit selected, said switchhaving a wiper adapted to put the line cut-oil relay in "series with'thelink circuit relay, and means for advancing the wiper, said the linecut-off relay, means controlled by said relays for changingthepotenti'alof the l nk c rcuit terminals to render'them non meansbeing controlled by selectable by establishing a locking circuit througha portion of the winding of the line cut on relay and cutting in anadditional winding on the link circuit relay. e

17. In combination, a line terminating in an automatic switch, aplurality of link circuit terminals banked in said switch, a linecut-off relay individual to the line, a relay individual to the linkcircuit select ed, said switch having a wiper adapted to put the linecut-off relay, in'series with the link circuit relay, and means foradvancing the wiper, said means being controlled by the line cutoffrelay, means controlled by the cut-off relay for cutting resistance'outof the c circuit and means controlled by thelink circuit relay forcutting reslstance into the circuit for changing the potential on theselected link terminals to render them nonselectable. r v V p 18; Incombination, calling lines, automatic switches individual to the callingline's, link circuits having multiplecontacts in the contact banks ofthe switches, each switch comprising a group of contacts all arranged ina single plane and a wiper having a limited range of movement andadapted to be moved successively in engagement with the contacts, astepping magnet, means con trolled over the calling line to cause thestepping magnet to'advance the wiper, means for holding the wiper inengagement with the contacts of a link circuit, means actuated by thestepping magnet for controlling subsequent release. actuation of thestepping magnet, and means rendered operative y the stepping magnet whenthe wiper is at the limit of its range of movement for disabling theholding means and permittingthe wiper to return to zero. I

19. In a switch, a bank of stationary con; tacts arranged in a singleplane, a wiper having a limited range of movement, said wiper beingnormally in zero position, a single magnet controlling the advance ofthe wiper step by step, means for opening the magnet circuit at a givenpoint and for causing the wiper to return to Zero, said means beingrendered active byrmovement of the wiper to the limit of its range ofmovement, means for closing the ci'rcuit'at'that point when the wiperreturns to'zero and means for openingthe circuit of the magnetat thewiper returns to another point when zero.

20. In 'combmation, automatic switches,

calling lines terminating in said automatic" testing magnet for; eachcalling line, said used, and a single relay serving as a liner cut-offfor the line and as a test relay for the switch. I

' 22. In combination, a line terminatingin a switch having bankcontacts, link circuits connected to said contacts, a relay individualto the line serving asa cut-off relay for the line and a'test relay forthe switch, a'signal relay individual'to the link circuit, both ofsaid'relays being connected in series by the switch and cooperating tochange the potential of the-corresponding bank contacts, a slow releaserelay individual to the link circuit, and a sleeve relay for the remoteend of the link circuit adapted to substitute the slow relay instead ofthe signal relay in the circuit of thecut-off relay. Y

3 23.- In a telephone system, a switch, a link circuit terminating inthe switch, a signal relay individual to the link circuit andconnected'in the third wire of the link circuit, a retarded releaserelayadapted to be substituted for the signal relay in-said third wireandmeans for substituting said release relay for the signal relay. i I24. In combinatiom 'a telephone line, an automatic switch individualthereto, said switch having a contact'bank, and contacts all lying in asingle plane, a movable wiper for engaging saidcontacts, said wiperhaving a limited range of movement, talking wires terminating in saidcontacts, means to advance the wiper step by step into selectiveengagement with one of saidcontacts and means for thereafterautomatically restoring the wiperto Zero by automatically advancing thewiper to the limit of its range of movement. r I

25. In combination, a telephone line; an automatic switch individualthereto, said switch having a contact bank, and contacts all lying in asingle plane, a movable wiper adapted to beadvanced in engagement withsaid contacts, said wiper having a limited rangeot movement, and talkingwires terminatmg in-said contacts, said sw tch having a single steppingmagnet for controlling the stepping of the "switch to a selected contactand for causing restoration'of the switch, and automatic means foroperating said magnet for causing a restoring advance to effectrestoration of the s'witc V 26;"In"combination, a switch having bankcontacts allarranged-ina single plane in the arc'of a circle,'and awiper for engaging said contacts, a calling line terminating .in thewiper of said switch, a plurality of link circuits terminating in thebank contacts, a

single stepping magnet controlled over the line for automaticallyconnecting the wiper to. the contact of an idle link circuit, means forholding the wiper in engagement'with aso connected contact and meanscontrolled by the stepping magnet for disengaging the holdin means. r

27. n' a telephone system,a telephone line, an automatic'switch havingwipers for said line, bank contact sets for said switch, telephonecircuits connected to said contact sets, 1 7

driving means for moving said wipers in a single plane only'to select acontact set of said switch, a relay operable over'the telephone line tocause such operation of the switch, a pawl for'holding the wipers intheir selected position, means responsive to an' interruption of thetelephone'line', to

cause said driving means to continue the ad vance of the wipers to apredetermined position, and means for thereupon disengaging said holdingpawl whereby said wipersare restored to normalb 28. In 'a' telephonesystem, a telephone line, an automatic switch having wipers for saidline, bank contact sets for said switch, telephone circuits connected tosaid contact sets, driving meanscfor moving said wipers in a singleplane-only to select a contact set of said switch, arelay operable overthe metallic circuit of the telephone line-to cause such operation ofthe switch, a pawl 'ffor holding the wipers in' their selectedposition,means responsive to an" interruption of the telephone line, tocause said-driving means to continue theadvance of the wipers to apredetermined position, and means for there-- upon disengaging saidholding pawl whereby said wipers are restored to normal.

29;"In a telephone system," telephone" lines,

automatic switches each having a wiper set for one of said lines, bankcontact sets for said'switches, telephone circuits multiply connectedto'said contactsets, driving means for each of said switches for movingthe wipers in a single plane only to'select one 7 of said contact sets,a'relay for each telephone line operable thereover to' cause suchoperation of the corresponding 'switch,"-a

pawl for each switch for holding the wipers in'their selected position,means responsive to an interruption of the telephone line, to

cause said driving means to continue'the ad v vance of the wipers of anoperatedswitch to a predetermined position, and means for thereupondisengaging said holding pawl whereby said wipers are restored tonormal.

30. Ina telephone system, telephone lines,

automatic switches each havinga wiper set for one of said lines,bankcontact sets for said switches, telephone circuits multiplyconnected to said contact sets, driving means for each of said switchesfor moving the wipers in a singleplane only to select one of saidcontact sets, a relay for each telephone line operable over the metalliccircuit thereof to'cause such operation of the corresponding switch, apawl for each switch for holding the wipers in their selected position,means responsive to an interruption of the telephone line, to cause saiddriving means to continue the advance of the wipers of an operatedswitch to a predetermined position, and means for thereupon disengagingsaid holding pawl whereby. said wipers are restored to normal. 1

31. In a telephone system, telephone lines, automatic switches eachhaving a wiper set for one of said lines, bank contact sets for saidswitches, telephone circuits multiply connected to said contact sets,each switch having its contact sets all arranged in asin- 1 gle planeand its wiper set having a limited range of movement and adapted to bemoved successively in engagement with the contacts, a stepping magnetfor'each switch, means controlled over a calling line, to cause thestepping magnet of the corresponding switch to advancethe wiper set,means for holding the wiper set in engagement with the contacts of atelephonecircuit, and means including a circuit operated upon theinitial actuation of the switch for subsequently causing said magnet toadvance an operated wiper set to the limit of its range of movement fordisabling the holding means and permitting the wiper set to return tozero.

32. In a telephone system, telephone lines, automatic switches eachhaving a wiper set for one of said lines, bank contact sets for saidswitches, telephone circuits" multiply connected to said contactsets,each switch having its contact sets all arranged in a single plane andits wiper set having a limited range ofgnovement and adapted tobe movedsuccessively in engagement with the contacts, a stepping magnet for eachswitch, means controlled over the metallic circuit of a calling line tocause the stepping magnet of the corresponding-switch to advance thewiper set, means for holding the wiper set in engagement with thecontacts of a telephone circuit, and means including a circuit operatedupon the initial actuation of the switch for subsequently causing saidmagnet to advance an operated wiper set tothe limit of its range ofmovement for disabling the holding means and permitting the wiper set toreturn to Zero. r

38. In a telephone system, a telephone line,

anautomatic switch having wipers for said line, bank contact sets forsaid switch,-operators link circuitsconnected to said contact sets,driving means for 'moving said wipers in a single plane only to select acontact settof an idle link circuit, a relay operable over the circuitor" the telephone line to cause, such operation of the switch, a pawlfor holding the wipers in their selected position, means controlled bythe operator to cause said driving means to continue the advance of thewipers to a predetermined position, and means for thereupon disengagingsaid holding pawl whereby said wipers are restored to normal.

' 34. In a telephone system, telephone lines, automatic switches eachhaving a wiper set for one ofsaid lines, bank contact sets for saidswitches, operators link circuits mul-' tiply connected to said contactsets, driving means for eachof said switches for moving the wipers in asingle plane only to select a contact set on an idle: link circuit,arelay for each telephone line operable over the circuit thereof tocausesuch operation of the corresponding switch, a pawl for each switchfor holding thewipers in their selected position, means controlled bythe operator to cause said driving means to continue the advance of thewiper set of an operated switch to a predetermined position, and meansfor thereupon disengaging said holding pawl whereby said wipers arerestored to normal.

35. A selector switch comprising contactsand cooperating wipers, a linerelay, a cutoff relay, a driving and release magnet, a driving circuitfor said-magnet controlled through normally opencontacts on the linerelay, and a release driving circuit for said magnet including normallyclosed contacts on the line relay and normally open offnormal contacts.r

36. A selector switch comprising contacts and cooperating-wipers, a linerelay, a cutoff and test relay, a driving and release magnet, a drivingcircuit for said magnet controlled through normally open contacts on theline relay, a release driving circuit for said magnet including normallyclosedcontacts on the line relay and normally open oil-normal contacts,and contacts on thecutoff and test relay for interrupting the drivingcircuit for saidmagnet.

37. A selector switch comprising contacts and cooperating wipers, a linerelay, a cutoff and test relay, adriving and release magnet, a drivingcircuit for said magnet con trolled through normally open contacts onthe line relay and normally closed contacts on the cutoif and testrelay, and a release driving circuit for said magnet including normallyclosed contacts on the line relay and normally open off-normalcontactsand normally closedcontacts on the cutoff and 7 of said switch, meansfor advancing the ment of the switch.

wipers of said switch over the bank contacts, means for stopping thewipers upon a set of said contacts if idle, a ratchet included in theadvancing means and a holding pawl therefor, means operative when thewipers are advanced to a predetermined position for disengaging saidpawl from the ratchet to allow the wipers to restore whereupon they areagain advanced over the bank contacts, and a restoring circuit forsubsequently operating the advancing means having a contact closed uponthe initial 40. In a telephone system, a telephone line, an automaticswitch, lines terminating in bank contacts of said switch, meanscontrolled over the line when calling for advancing the wipers of saidswitch over the bank contacts, means for. stopping the wipers uponengagement with a set of idle contacts, a ratchet included in saiddriving means and a holding pawl therefor, mechanical means operativewhen the wipers are advanced over all of the contacts if busy for'disengaging said pawl from the ratchet to allow the wipers to restorewhereupon they are again" advanced under control of the line .to seek aset of idle contacts, and a restoring circuit for subsequently operatingthe advancing means having a contact closed upon the initial movement ofthe switch.

41. In a telephone system, an automatic switch, a group of linesterminating in contacts of said switch, means for driving said automaticswitch over the contacts of said group, means for causing said switch tostop upon a set of electrically distinguished contacts, a restoringspring for said switch, means operated when said automatic switchreaches a pre-determined position to allow said spring to restore saidswitch to its normal position whereupon it is again driven over thecontacts of said group, and means actuated by said driving means forpreparing the driving means for effecting subsequent restoring advanceof the switch. 42. In atelephone system, an automatic switch, a group oflines terminating in contacts of said switch, means for driving saidautomatic switch over the contacts of said group, means for causing saidswitch to stop upon a set of electrically distinguished contacts, aratchet, a pawl normally in engagement with said ratchet for holdingsaid switch in its actuated position, mechanical means operated whensaid automatic switch reaches a predetermined position for withdrawingsaid pawl from said ratchet to allow saidswitch to restore to-its normalposition whereupon it is again driven over the contacts of said group,and means actuated by said driving means for preparing the driv- 7 ingmeans for effecting subsequent restoring advance of the switch.

43. In a telephone system, an automatic switch, a group of linesterminating in a row of contacts of said switch, means'for driving saidautomatic switch over the entire row of said terminals, a ratchet, a.pawl normally in engagament with said ratchet for preventing therestoration of saidswitch,

means for causing said switch to stop upon a set of electricallydistinguished contacts, mechanical means operated when said au tomaticswitch reaches the end of said roW to withdraw said pawl from saidratchet to allow said switch to return to the beginning of said row,whereupon said switch' is again driven over said row, and means actuatedby said driving means for preparin'gthe driving means for effectingsubsequent restoring advance of the switch. 7

44. In a telephone system, atelephone line,

an automatic switch, lines terminating in bank contacts of saidswitch,means controlled over the line when calling for advancing thewipers of said-switch over the bank contacts, means for stopping thewipers upon engagement with a set of idle contacts, 'a ratchet includedin said driving means and a holding pawl therefor, mechanical means Ioperative when the wipers are advanced over all of the contacts'if busyfor disengaging said pawl from the ratchet to allow the wipers torestore whereupon they are again advanced under control of the line toseek a set of idle contacts, and circuit connections thereafterresponsive to an interruption of the line for causing the adv'anc-.

ing means to actupon the wipers to again move them over the contacts toa restoration thereof. r In witness whereof,I hereuntosubscribe my namethis 17th day ofAprilA. D51916.

bring about HARRY a. WEBST.ER.

